Continuous rolling mill train for rolling bar stock

ABSTRACT

IN A CONTINUOUS ROLLING MILL TRAIN FOR BAR STOCK EACH THREE SUCCESSIVE ROLLING MILL STANDS ARE PROVIDED WITH A COMMON DRIVE. THE CENTRAL STAND OF EACH SET OF THREE STANDS IS A VERTICAL STAND SO THAT INSIDE THE THREE STAND SET THE ROLLED PRODUCT IS NOT TWISTED.

March 2, 1971 BLlNN 3,566,657

' CONTINUOUS ROLLING MILL TRAIN FOR ROLLING BAR STOCK Filed Nov. 22, 1968 United States Patent US. Cl. 72-234 5 Claims ABSTRACT OF THE DISCLOSURE In a continuous rolling mill train for bar stock each three successive rolling mill stands are provided with a common drive. The central stand of each set of three stands is a vertical stand so that inside the three stand set the rolled product is not twisted.

The invention relates to a rolling mill train for rolling bar stock, particularly of circular cross-section, which is intended to be used especially as a wire rod mill.

The object of this invention is to provide a rolling mill train of this type which is especially low priced and without giving up too many advantages which are available in the expensive continuous trains with an H-V- arrangement of the individually driven and loop regulated roll stands, such as tension and twist free rolling.

One way to lower the investment costs would consist in using a group drive for the roll stands instead of an individual drive. However, this would eliminate the advantage of a tension free rolling, at least within the stand groups. Twist free rolling can be maintained if in spite of a group drive the H-V-arrangement of the roll stands is retained throughout. But this requires a maximum number of expensive vertical stands and the investment savings would be restricted to the substitution of the in dividual drive for a group drive.

It is an object of the invention to find a compromise solution on the basis of the broad idea generally stated above for this type of rolling mill train in which the number of expensive vertical roll stands required is reduced to a minimum, in which twist-free rolling is maintained to the greatest possible extent and-if twisting is necessarythis can be done tension free. When building bar stock rolling mills one should strive to avoid twisting of bar stock by twist bushings under tension. Light tension or drawing without twisting is quite admissible. Similarly twisting without drawing is harmless.

The invention is based on a continuous rolling mill train for bar stock which has roll stands driven together by groups and which have within these groups alternately a horizontal and vertical position of the rolls whereby the for only two stands, namely for one horizontal stand and tension free over loop formers between the groups.

The invention is characterized in that the stand groups consist respectively of two horizontal stands and one vertical stand located therebetween. Accordingly the essence of the invention is the selection of three-unit stand groups consisting of two horizontal outer stands and one central vertical stand which are driven together by groups.

In this connection it is pointed out that group-drives as far as it is known from the prior art comprise either two stands or four and more stands. It is already known from German Patent No. 1,084,672 to stagger a set or group of three stands but this patent discloses a group drive for only two stands, namely for one horiozntal stand and one vertical stand. The third stand has a separate drive. The purpose of this arrangement is to roll without using ice the vertical stands either multiple core or fiat, or to produce a pure H-V-arrangement by moving in each instance the central horizontal stands out of the rolling line. The three stands of the staggered groups are never all used at the same time. Therefore this prior art arrangement is not concerned with the problem of saving vertical stands in a rolling mill train for bar stock which operates to the greatest possible extent twist-free, because if with this known rolling mill train rolling is carried out twist-free in an H-V-arrangement of the stands a horizontal stand is always followed by a vertical stand.

The object of this invention is not exhausted with the selection of a group drive for sets of three stands to save costs but other objects and advantages of the invention will become apparent from the following description of a rod mill train according to the invention illustrated in the accompanying drawing.

With reference to the single drawing it will be understood that the material to be rolled arrives from a roughing mill (not shown) and travels in the direction of the arrows through four three-stand sets or groups A, B, C, and D, thereafter through a two-stand group B, then again through a three-stand group F and is finish rolled in a last individually driven vertical stand 18.

The three-stand groups A, B, C, -D and F each consist of two outer horizontal stands 1, 3, 4, 6, 7, 9, 10, 12, 15, 17 and between them are mounted vertical stands 2, 5, 8, 11, 16. The two stand group B has a horizontal stand 13 and after it is mounted one vertical stand 14. Within the stand groups the stands are mounted as closely together as possible.

The three-stand groups are driven together in a known manner by common motors 20 over common gear-units 21. The speed of the motors 20 may be suitably regulated. The stands of the twin-group B have a common motor 22 and a common gear-unit 23. The single-stand 18 has a drive motor 24. Between all the stand groups and in front of the end stand 18 loopers are provided. The size of the loops may be limited in a known manner by regulating the speed of rotation of the drive motors 20, 22 and 24.

In the case where as shown in association with the individual stands one rolls substantially with a squareoval roll pass pattern although the invention is not limited to this calibration, it will be found that within the stand groups, triple groups as well as twin groups, it is not necessary to twist with twist bushings due to the alternation of horizontal and vertical stands which occurs here. Accordingly one is free to roll here with a light tension which is favorable in respect of the reduction of the material. However, the H-V-arrangement is interrupted from group to group, aside from the transition from the twin group E to the last triple stand F. In this manner it may be necessary under certain conditions to twist at the places where, in opposition to the pure H-V-arrangement, in each instance one vertical stand is saved, namely between the groups A and B as well as C and D. There is no problem in twisting here because due to the loop formations between the stand groups rolling is effected without tension.

As a result one obtains a continuous train which is almost twist-free and in which, as shown in the embodiment described and illustrated herein, one effects a saving of not less than four expensive vertical stands in view of the fact that one is forced to twist only in two places. Furthermore the cost saving group drive is used for a stand number, namely three, in which the rolling with a light tension may be easily controlled in spite of a rigid series of motor rotations.

The limitation to three stands per group leads also to a sufficiently large number of loops so as to furnish without tension in the rolled productsavings due to the reduced number of vertical stands, the group drive, the shorter construction of the train, the reduced number of loops as Well as the reduced cost of electrical equipment, since the number of the motors to be regulated is also substantially smaller. These are all advantages which 7 actually do not have a causal connection with the group drive arrangement and constitute an unexpected result.

The twin group E and the vertical end stand 18 afford in connection with the intermediate triple group F to carry out the last four passes in a pure H-V-arrangement of the stands, thus twistfree.

The rolling mill train according to the invention has actually been designed preferably for rolling round material but this rolling mill train may also be used to roll profiles or flat material if the vertical stands are not used, or for the purpose of making edge passes on flat material, are not all used. Due to the thus reduced number of working stands one can of course only produce heavier according to another feature of the invention so-called combined rolling mill stands such as shown in US. Pats.

No. 1,072,676 and No. 2,603,989 between the horizontal stands arranged in a rolling line, each of said groups including a pair of horizontal roll stands and an intermediate vertical roll stand between said horizontal stands, means for driving all of the stands in each of said groups in common, said groups having a spacing therebetween in said rolling line to provide for the formation of a loop between said groups.

2. A continuous rolling mill train in accordance with claim 1 including a plurality of alternating horizontal and vertical roll stands in said rolling line for performing additional rolling passes on the bar stock processed in said plurality of groups of roll stands.

3. A continuous rolling mill train in accordance with claim 2 wherein said last roll stand in said plurality of alternating horizontal and vertical roll stands is a vertical stand.

4. A continuous rolling mill train in accordance with claim' 3 wherein said plurality of alternating horizontal and vertical roll stands includes a first group of roll stands having a horizontal and vertical roll stand adjacent the last of said plurality of groups of roll stands, means for driving all of the stands in said first group in common, a second group of roll stands adjacent said first group including a pair of horizontal roll stands and an intermediate vertical roll stand between said horizontal stands and means for driving all of the stands in said first group in common.

5. A continuous rolling mill train in accordance with claim 4 wherein said intermediate vertical stand in said plurality of groups of roll stands comprises a combined rolling mill stand.

References Cited UNITED STATES PATENTS 3,256,727 6/1966 Takaishi 72234 3,382,697 5/1968 Neumann 72226 3,383,896 5/1968 Blinn 72-226 FOREIGN PATENTS 1,328,186 4/1963 France 72-234 MILTON S. MEI-IR, Primary Examiner 

